A mobile station performing soft handover (SHO) provides much interference to multiple cells. Accordingly, there is a known conventional technique for increasing a cell throughput by setting the transmission rate of a mobile station performing soft handover to be lower than the transmission rate of a mobile station not performing soft handover.
For example, according to Non-Patent Document 1, a cell throughput is enhanced by providing the maximum value such as 256 kbps or 512 kbps to a mobile station performing soft handover.
In contrast, when traffic is off-peak, a radio quality is rather improved if the transmission rate of a mobile station performing soft handover is set to be higher without such maximum value provided.
In other words, the providing of the maximum value of the transmission rate to the mobile station performing soft handover in a fixed manner deteriorates the radio quality at a time of off-peak traffic.
[Non-Patent Document 1] 3GPP TSG-RAN TR25.896 V6.0.0